Volume-varying and compressionrelieving means for the combustion chambers of internal combustion engines



Aug. 27, 1935. A A NE 2,012,895

VOLUME VARYING AND COMPRESSION RELIEVING MEANS FOR THE COMBUSTIONCHAMBERS OF INTERNAL COMBUSTION ENGINES Filed March 51, 1932 Al N Z Ix45 as 3 Hal INVENTOR- Arthur A. Sidney ATTORNEY Patented Aug. 27, 1935VOLUME-VARYING AND COMPRESSION- RELIEVING MEANS FOR THE COMBUS- TIONCHAMBERS OF INTERNAL COM- 1 BUSTION ENGINES Arthur Alexander Sidney,Thornton Heath, England, assignor to Bryce Limited, a company of GreatBritain Application March 31, weasel-m1 No. 602,340 In Great BritainApril 2, 1 31 2 Claims.

This invention-relates to volume-varying and compression-releasing meansfor the combustion chambers of. internal combustion engines and has forits object to provide means whereby the compression ratio of the enginemay be reduced to zero, set at a normal value or set at an increasedvalue.

A variable compression ratio is particularly desirable in the case ofcompression ignition or heavy oil engines. In order to obtain the airtemperature necessary for self ignition when starting such an enginefrom the cold condition, a high compression ratio has to be employed.When the engine is in normal operation, however, the heating of theairin the cylinder by the hot cylinder walls results in a considerablyincreased compression pressure and a lower compression ratio is thendesirable in order to reduce the stresses in the various parts of theengine.

Furthermorain brder to reduce the resistance against initial rotation ofthe engine crank shaft, it is desirable to be able to release thecompression appreciably.

All the above stated three requirements are fulfilled by the presentinvention.

The invention comprises a cylindrical chamber communicating at one endwith a cylinder chamber of the engine and having a pair ofoppositely-directed seats, a disc disposed transversely of said chamberwith substantial clearance between its periphery and the chamber walland having a face on each ofits front and. rear surfaces adapted tocooperate, respectively, with the seatings in the chamber, and means formoving the disc, axially ofthe chamber to locate it positively in eitherof its extreme positions to cooperate with one or the other of theseatings,

or to locate it positively in an intermediate position.

Further features of the invention'will be hereafter described orindicated.

In the accompanying drawing:-

Figure 1 is a part sectional side elevation of a compression ignitionengine embodying the invention.

Figure 2 is a section on the line 22 of Figure 1 with the cover for thevalve mechanism re- I moved.

Figure 3 is a fragmentarysection through the cylinder head, on anenlarged scale.

In carrying the invention into effect by the embodiment thereofillustrated in the drawing, the cylinder I of an engine is provided witha detachable cylinder head 2 having asubstantially cylindrical cavity 3which forms the combustion chamber of the engine, the said engine beingpreferably so constructed that its working piston approaches the innerface of the cylinder head as closely as is mechanically possible so thatthe bulk of v the charge is confined in the chamber 3. The outerenlarged end of thechamber 3 is closed by a cover 4 secured to thecylinder head 2 by studs 5 and formed with a bore in which the stem 6 ofa member for regulating the volume of the combustion chamber is slidablymounted.

A spindle I, provided with a hand-wheel 8, is screw-threaded into abridge-piece 9, which bridge-piece is attached to the cylinder head 2,and said spindle is connected to the stem 6 by means of a pin [0. Thestem 6 is formed with a. disc head ll having front and back faces l2 andI3 adapted to engage seats l4 and I5, respectively. The seating l4isformed in the cylinder head 2 and the seating I5 in the cover 4.

The circumference of the disc head II is pref- 20 erably smaller thanand has a sliding fit in the bore of the combustion chamber 3. A channelll, formed inthe cover 4, extends between a point in the chamber 3outwardly of the seat l5 and the exhaust outlet l8 of the engine. Bymeans 25 a consequent high compression ratio for the en- 80 gine issecured, or said disc head may be withdrawn away from the cylinder 1 soas to move its face l3 against the seat l5 so as to secure a combustionchamber of maximum volume and,

therefore, a low compression ratio for the engine. 35

The cylinder head Zis provided with an aperture l6 communicating withthe combustion chamber 3 in which may be inserted an ignition device,for example either a fuel sprayer, in the case of a, compressionignition engine, or a spark 40.

plug, in the case of a hydrocarbon or like engine. I

In the operation of the invention, particularly in its application tocompression ignition engines, when starting the engine, the hand wheel8' is turned in a direction to set the face I 2 of the disc head I Iagainst the seat It so as to secure a high compression ratio in thechamber 3. It is thus possible to obtain the necessary ignitiontemperature of the charge of air even when the engine is cold. Later on,however, when the engine has become warm, the continued use of this highcompression ratio would result in abnormally high compression pressuresand consequent engine stresses as the result of the higher initialtemperature of the air which is being compressed,

and thedisc head II is, therefore, moved to its low compression positionin which it's valve I3 is seated against the seat l5.

' As previously stated, the piston of the engine is made to approach theinner face of the cylinder head closely, so as to leave the minimumpossible clearance betweenit and the cylinder head. By this means,substantially the entire contents of the cylinder l areconcentrated atthe moment of ignition in the combustion chamber 3 thereby obtaining thehighest possible efliciency of operation.

The clearance provided between the circumference of the disc head II andthe bore of the combustion chamber 3 enables the cylinder charge toescape, whenever the disc head H is in an intermediate position, bywayof a channel I'I, formed in the cover 4, which channel may communicate.either with the atmosphere or with the exhaustconduit in-the cylinderhead. The cylinder compression may thus be released in order tofacilitate the initiation of rotation of the engine crankshaft whenstarting.

Itis to be-understood that the-invention is not in, said combustionchamber communicating at its inner end with the cylinder and at itsouter end with the exhaust outlet, said combustion chamber having aseat, adjacent its outer end and a second seat between its ends, a discdisposed 'transverselyof said chamber with substantial clearance betweenits periphery and the chamber wall, said disc having a face on each ofits front and rear surfaces adapted, respectively, to cooperate withsaid seats of the chamber, and means for moving the disc 'axially of'the chamber to locate it positively in either of its extreme positionswith one or the other of its faces in contact with one or other of theseats to vary the volume.

of the combustion chamber, or to locate it in an intermediate positionto relieve the compression.

2. In an internal combustion engine, a cylinder, a head for the cylinderhaving a cylindrical combustion chamber and an exhaust outlet therein,saidcombustion'chamber communicating at its inner end with the enginecylinder and at its outer end with the exhaust outlet, said combustionchamber having an annular seat at its outerend and an oppositelydirected annular seat axially' displaced from said other seat, a discdisposed transversely of said chamber between said seatings withsubstantial clearance between its periphery and the wall of the chamber,said disc having an annular face on its front surface and 'an annularface on its rear surface, and means for moving the disc axially of saidchamber to seat one of its annular'faces at'one end of its movement onthe first-named annular seating or to seat its other annular face on thesecond-namedannular seating at the other end of its movements to varythe volume of the combustion chamber, or to position the disc betweenits extreme positions to relieve the compression.

ARTHUR ALEXANDER SIDNEY.

